An octagonal brick versio
An octagonal brick version of this structure was engineered for the Santa Maria del Fiore by Brunelleschi, and a famous Roman one features an Oculus. Four pendentives support this structure in Istanbul's Hagia Sophia, and nine of these structures sit atop a prominent cathedral in Moscow. For 10 points, name this architectural feature seen atop the Pantheon and the Taj Mahal, which occurs on St. Basil's Cathedral in an "onion" shape.
An octagonal brick version of this structure was engineered for the Santa Maria del Fiore by Brunelleschi, and a famous Roman one features an Oculus.
{Domes}